APBA Inboard Category

When you hear the roar of automotive engines and catch a glimpse of giant roostertails, chances are pretty good that inboards are on the water. As the largest category in the APBA, Inboard racing classes include both runabouts and hydroplanes that are fast, fun and LOUD. Classes span from wild Jersey Speed Skiffs (70mph) to supercharged 1,500 horsepower Grand Prix Hydroplanes (170 MPH). The minimum age for racing in this exciting category ranges from 14 to 21.

Inboard racing requires an unmatched level of teamwork and professionalism, as well as a family atmosphere with life long bonds between owners, drivers and crew members; and that is exactly what powerboat racing is all about.

Inboard racing classes consist of both Runabout and Hydroplane classes. You can tell a boat’s class by the letter(s) next to the boat number. All inboard drivers are required to wear a racing helmet and life jacket as well as other protective gear such as fire-resistant Nomex and cut resistant Kevlar. Drivers who race inboards with an enclosed cockpit (capsule) are required to pass APBA capsule training and certification every two years. Nobody plans to flip, but it does happen from time to time… and when it does happen, the training pays off.

Inboard Runabouts, or flatbottoms, come in both the open cockpit and capsule variety. Flatbottoms are known for their long lean shape, which allows the boat to slice through water as they move at speeds of 100+ MPH. Got a friend? Some runabouts run with two racers on board – a driver and a mechanic.

Hydroplanes glide over the water on a cushion of air, with only the propeller and sponsons on each side touching the water while air rushes under the hull, giving the boat the “lift” it needs to skim across the water. These bad boys are fast, with some classes running at speeds in excess of 150mph – Inboard hydroplane classes range from 1 liters (T-Boats) to the 1500hp supercharged Big Block Chevrolet V8 Grand Prix (GP). All inboard hydros utilize a capsule safety cell as well as racing lap and shoulder belts. Controls are similar to those of an automobile – steering wheel, accelerator pedal, rear view mirrors – but no brakes!

WATCH OUT for roostertails! If an inboard hydro is in front of you, chances are you’re about to get blasted with a wall of water from the giant roostertail of the boat in front of you. Racing into a turn favors the leader, with those behind having to deal with roostertail fallout!


1 Litre (“Y” class) hydroplanes are small, light and lightning quick, racing to speeds over 105 mph. While supercharging is not allowed, other modifications are encouraged. Engines are automotive or marine based, 2 or 4-cycle style. Maximum limit of 2-cycle is 1160 cc and maximum limit of 4-cycle is 1315 cc. The most common engines are from 2-cycle personal water crafts boats!

1 Litre Specifications

Minimum Length:13′ 6
Minimum Weight:750 or 825 lbs including driver depending on boat length
Engine:Fall into 4 categories with varying modification limits. 1030 cc, 1160 cc, 1260 cc, and 1315 cc
Fuel:Racing fuel per APBA specs
Approximate Speed:105mph

1.5 Litre Stock (“T” class) hydroplanes race at 90+ mph. These small, light and racy hydros are a great starting point for young drivers or for budget teams. They generate all the competitive excitement of the bigger classes, but their smaller size, virtually stock components, and dependable 4 cylinder Toyota engine add a degree of economy to following the boat racing trail.

1.5 Litre Stock Specifications

Minimum Length:14′ 6″
Minimum Weight:825 lbs including driver
Engine:4 cylinder Toyota SOHC 1587cc (97 cubic inches)
Fuel:Gasoline per APBA specs
Approximate Speed:90mph

The 2.5 Litre Modified (“A” class) hydroplane races at speeds over 130 mph – creatively. Few engine restrictions apply beyond prohibiting superchargers and setting a displacement limit of 166 cubic inches; engine modifications are limited only by the racer’s imagination.

2.5 Litre Modified Specifications

Minimum Length:16′
Minimum Weight:1225-1325 lbs. depending on engine type
Engine:Maximum displacement of 166 cubic inches
Fuel:Methanol (alcohol) or Racing gasoline per APBA specs
Approximate Speed:130mph

2.5 Litre Stock hydroplanes (“S” class) race to 100-plus mph, using 145 horsepower marine-based 2000 and 2300 Ford engines. S-boats offer very exciting side-by-side racing at a reasonable cost. Driving skill is paramount here, and driver development is inevitable, making this class an excellent stepping stone to bigger, higher-powered classes.

2.5 Litre Stock Specifications

Minimum Length:13′ 6″
Minimum Weight:1025 lbs. including driver
Engine:2000 and 2300 Ford Inline 4 Cylinder
Fuel:Gasoline per APBA specs
Approximate Speed:100+mph

E 350 hydroplanes (5 Litre boats) race to speeds of 115 mph, powered by mildly modified marine-based stock 305 Chevrolet and 302 Ford V-8 engines (285 horsepower). Engine modifications are limited, putting a premium on driver skill, with great competition at every event. These guys and gals duke it out, every time!

E 350 Specifications

Minimum Length:16′
Minimum Weight:1525 lbs. including driver
Engine:305 Chevrolet or 302 Ford V-8
Fuel:Gasoline per APBA specs
Approximate Speed:115mph

Crackerbox (“P”) is one of the oldest Inboard Runabout classes, distinguished by the 2-person team of driver and rider seated side by side at the rear of the hull. A powerful modified engine, mounted amidships, powers these sprinting flatbottom hulls in impressively competitive races.

Crackerbox Specifications

Minimum Length:15′ 6
Minimum Weight:1250 lbs.
Engine:Small block V-8 automotive based, hot rod innards, carburetion or fuel injection allowed
Fuel:Methanol ‘alcohol’ or racing gasoline per APBA specs
Approximate Speed:

Grand National Hydroplane, aka GNH or 7 Litre, is the largest non-supercharged Inboard hydroplane class. Powered usually by big block Chevrolet based engines (up to 511 cubic inches) with an hot rod racing engine(750+ horsepower), the highly competitive GNH’s have 150 mph capability and throw 70-foot roostertails, thrilling drivers and fans alike.

Grand National Hydroplane Specifications

Minimum Length:20′
Minimum Weight:2220 lbs.
Engine:Big block automotive and marine based racing V-8 engines, up to 511 cubic inches
Fuel:Racing gasoline per APBA specs
Approximate Speed:150mph

Grand Prix Hydroplane – supercharged competition! This professional level GP class provides all the noise and excitement you can handle. The 1500 horsepower blown V-8s, based on big block Chevrolet design, make the most noise and throw the biggest roostertails this side of anywhere! Limitations are few; beyond the 468-cubic inch engine displacement, it’s Hot Rod City and up to the ingenuity of the builder. Grand Prix hydros are the biggest and baddest of the bad!

Grand Prix Hydroplane Specifications

Minimum Length:23′
Minimum Weight:2700 lbs. including driver
Engine:Supercharged Big Block Chevrolet V-8, maximum displacement 468 cubic inches
Fuel:Methanol (alcohol) or racing gasoline per APBA specs
Approximate Speed:170mph

Jersey Speed Skiff is an exciting and dynamic class of Inboard Runabout. In competition, the boat must carry a crew of two (driver and riding mechanic) seated side by side, strapped inside a steel tubing roll cage. The 300-plus horsepower Skiffs are a wild ride; they spend a lot of time airborne, bouncing around, rolling sideways to seemingly impossible angles, at 80 MPH. The riding mechanic holds on tight, while the driver stays on course.

Jersey Speed Skiff Specifications

Minimum Length:16′
Minimum Weight:1650 lbs.
Engine:283 or 305 cubic inch Chevrolet V-8
Fuel:Pump Fuel or Gasoline per APBA specs
Approximate Speed:80mph

K Racing Runabouts (K-Boats) are a professional class of propeller-driven Inboard Racing Runabouts, using virtually unlimited engines and fuel. Basically, anything goes. Drivers must be 21 years old and qualified, as these boats are extremely fast (competition speeds over 100 MPH, and a Kilo record of 147.265 MPH).

K Racing Runabout Specifications

Minimum Length: 17′
Minimum Weight: 2250 lbs. including driver
Engine: Supercharged, maximum 470 cubic inch
Fuel: No fuel requirements
Approximate Speed: 100 mph

The National Modified hydroplane (NM) offers speeds of 140 mph to the serious competitor, utilizing automotive and marine non-supercharged engines ranging from 4-cylinder and V-6 up to 368 cubic inch V-8 engines, carbureted and fuel injected.

National Modified Hydroplane Specifications

Minimum Length:17′
Minimum Weight:1255-1900 lbs. depending on engine type including driver
Engine:4 cylinder, V-6 and up to 368 cubic in. V-8 configurations
Fuel:Methanol ‘alcohol’ or racing gasoline per APBA specs
Approximate Speed:140mph

Sportsman Entry is a fun, affordable entry level runabout class with a maximum speed of 85 mph using only GM cast iron small block and cast iron heads derived from passenger or truck model vehicles, and abiding by inboard Runabout and safety rules.

Sportsman Entry Specifications

Minimum Length:16′ – Min Width: 72″
Minimum Weight:1850 Lbs. (including driver and safety equipment) including driver
Approximate Speed:

Super Stock (SS) is a powerful, fast (100+ MPH) Inboard runabout class. These exciting flatbottom hulled boats are powered by high-winding, 427 cubic inch big block Chevrolet engines, based on the venerable L88 design, which must be mounted rear of amidships and drive forward through a V-drive. Drivers often run both Super Stock and Pro Stock, so you may see boats with SS/PS next to the number.

Super Stock Specifications

Minimum Length:16′
Minimum Weight:1950 lbs. including driver
Engine:427 cubic inch big block Chevrolet engine
Fuel:Racing gasoline per APBA specs
Approximate Speed:100mph

Sportsman Advanced Class.

Sportsman Advanced Specifications

Minimum Length: 
Minimum Weight: 
Approximate Speed: